0:00:02 > 0:00:04My name's Steve Backshall.
0:00:06 > 0:00:09And this...is Deadly Pole To Pole.
0:00:09 > 0:00:11Ohhh!
0:00:11 > 0:00:13From the top of the world to the bottom.
0:00:13 > 0:00:15Whoa!
0:00:15 > 0:00:17Deadly places.
0:00:17 > 0:00:18Deadly adventures.
0:00:18 > 0:00:20And deadly animals.
0:00:21 > 0:00:24And you're coming with me, every step of the way!
0:00:26 > 0:00:27Arghhhh!
0:00:30 > 0:00:34This time the team and I have come to Yellowstone, it's the oldest
0:00:34 > 0:00:38national park in the world, routinely the coldest place
0:00:38 > 0:00:41in North America, and also a sensational place
0:00:41 > 0:00:43to go looking for winter predators.
0:00:45 > 0:00:49We're on the trail of an American giant...
0:00:49 > 0:00:51Be careful, Steve.
0:00:51 > 0:00:52..specialist hunters...
0:00:54 > 0:00:56..and the voice of the wilderness.
0:00:57 > 0:00:59HE HOWLS
0:00:59 > 0:01:02White Fang himself, the wolf.
0:01:02 > 0:01:04Go, go, go!
0:01:04 > 0:01:06We've just seen a couple of wolves.
0:01:06 > 0:01:08Oh, wow!
0:01:10 > 0:01:13Yellowstone spans three North American states -
0:01:13 > 0:01:15Montana, Idaho and Wyoming.
0:01:18 > 0:01:20It's a protected pristine wilderness the size
0:01:20 > 0:01:22of a small country.
0:01:27 > 0:01:30My main mission here is to go looking for the top dog
0:01:30 > 0:01:34in North America, and my favourite animal in the world, the grey wolf.
0:01:38 > 0:01:40They're intelligent, complicated
0:01:40 > 0:01:44cooperative hunters, and one of the most ruthless
0:01:44 > 0:01:46and relentless of all predators.
0:01:47 > 0:01:50In this wintry wilderness the wolf rules,
0:01:50 > 0:01:53but they're so canny that finding and filming them
0:01:53 > 0:01:54will be almost impossible.
0:01:59 > 0:02:01Their territories can span hundreds of square miles.
0:02:03 > 0:02:05They're incredibly perceptive and will doubtless
0:02:05 > 0:02:07sense us before we see them.
0:02:10 > 0:02:13We're going to need to be adaptable to stay on their trail.
0:02:14 > 0:02:16This vehicle is absolutely brilliant.
0:02:16 > 0:02:19Essentially someone's just taken an old van,
0:02:19 > 0:02:22pulled the wheels off and welded a tank to the bottom of it.
0:02:24 > 0:02:27To have any chance of seeing wolves, I'm going to need some luck,
0:02:27 > 0:02:31all of my tracking skills and an eagle-eyed crew.
0:02:32 > 0:02:34Well, I suppose you can't have everything.
0:02:38 > 0:02:42Method number one is to get eyes on the wolf's favoured prey.
0:02:45 > 0:02:49We've just spotted from the road some brown shapes
0:02:49 > 0:02:51moving slowly on the other side of this tree line here,
0:02:51 > 0:02:54so we'll approach really quietly and see if we can get a look.
0:03:08 > 0:03:12Down at the river's edge there are several elk,
0:03:12 > 0:03:15it's a large species of deer, and here in Yellowstone
0:03:15 > 0:03:18this is the main prey species that the wolves are after.
0:03:20 > 0:03:23At this time of year they're at a considerable disadvantage
0:03:23 > 0:03:25because they have to break down through the snow
0:03:25 > 0:03:29to get at the grass, and also to munch on these conifers,
0:03:29 > 0:03:31none of which have an awful lot of nutrients in them.
0:03:31 > 0:03:34So as the winter goes on they start getting weaker and weaker,
0:03:34 > 0:03:37and more and more ripe pickings for the wolf.
0:03:40 > 0:03:42The wolves know the elk are here,
0:03:42 > 0:03:45and may well be within striking distance.
0:03:49 > 0:03:53We've pulled up because it appears that something quite dramatic
0:03:53 > 0:03:56has happened alongside the road here.
0:03:56 > 0:04:01Loads of fur at the verge...
0:04:01 > 0:04:04and what looks like a chunk of pelt right here.
0:04:07 > 0:04:10Look at that. Wow.
0:04:10 > 0:04:17That is a fairly complete chunk of skin from an elk.
0:04:18 > 0:04:20This, though, has been dragged up onto the road,
0:04:20 > 0:04:22the kill didn't happen here,
0:04:22 > 0:04:23it looks like it happened just over there.
0:04:25 > 0:04:30Wow, there is sign absolutely everywhere.
0:04:33 > 0:04:35So when you're approaching something like this,
0:04:35 > 0:04:38it's a bit like approaching a crime scene, you've got to be
0:04:38 > 0:04:42very careful where you put your feet, because all of these marks
0:04:42 > 0:04:44- though they look like a mess -
0:04:44 > 0:04:46they're actually signs of what's gone on here,
0:04:46 > 0:04:51and that looks like it was the epicentre...of the kill.
0:04:51 > 0:04:55Yeah, oh, my goodness, there is blood everywhere, look at that!
0:04:57 > 0:05:01That's really kind of gory,
0:05:01 > 0:05:05and instantly to me this just says "wolf kill".
0:05:05 > 0:05:09You might have five or six animals all competing for food, they'll get
0:05:09 > 0:05:12their teeth stuck into it, they'll wedge down with their big paws
0:05:12 > 0:05:15on straight legs and just shake,
0:05:15 > 0:05:17using all of the muscularity in their neck,
0:05:17 > 0:05:20and it ends up kind of looking like a butcher's shop floor.
0:05:24 > 0:05:27I know some people might think I'm insane,
0:05:27 > 0:05:32but that to me is a really wonderful sight. It's poo.
0:05:32 > 0:05:35It's poo, but it's twisted with a tapered end
0:05:35 > 0:05:40and full of deer hair. And it's wolf,
0:05:40 > 0:05:43that is definitely wolf poo.
0:05:43 > 0:05:45It's difficult to tell how fresh it is
0:05:45 > 0:05:48because it's obviously been really cold here,
0:05:48 > 0:05:53so it's frozen solid, but they were here within the last couple of days.
0:05:54 > 0:05:55WOLVES HOWL
0:05:55 > 0:06:00The wolf pack is more than just a family unit, it's an organised team
0:06:00 > 0:06:02that opens up endless opportunities.
0:06:04 > 0:06:07Working together, they can bring down prey far larger
0:06:07 > 0:06:09than any single wolf could handle.
0:06:14 > 0:06:16When prey is spotted, the lightest
0:06:16 > 0:06:18and fastest wolves take the lead...
0:06:20 > 0:06:22..while others circle around the quarry,
0:06:22 > 0:06:26or save their energy - waiting to take over when the others tire.
0:06:29 > 0:06:32They target a weak, old, young or injured animal,
0:06:32 > 0:06:34separating it from the herd.
0:06:38 > 0:06:41Once they have their target alone and vulnerable,
0:06:41 > 0:06:45the whole pack charge in. It's a gruesome end
0:06:45 > 0:06:47for this elk, but ultimately ensures
0:06:47 > 0:06:50the elk herd stays strong, their weaker members
0:06:50 > 0:06:52falling to one of the world's top predators.
0:06:54 > 0:06:57'Unfortunately, here the trail's gone cold.
0:06:57 > 0:06:59'It's time to get back on the road.'
0:07:06 > 0:07:07The snow wagon rumbles on.
0:07:11 > 0:07:14But then, just the lead we were hoping for.
0:07:14 > 0:07:17A pack has been spotted 70 miles to the north.
0:07:17 > 0:07:21It's a big journey, but probably our best chance.
0:07:21 > 0:07:23It's all very different here, we're lower in altitude
0:07:23 > 0:07:24and there's less snow.
0:07:24 > 0:07:29Our plan now is just to drive this road, keeping our eyes peeled
0:07:29 > 0:07:30for any sign of a wolf.
0:07:30 > 0:07:35Really it's all now down to my team keeping their eyes on the prize.
0:07:37 > 0:07:39'This could be a very long car ride.'
0:07:45 > 0:07:47We've tried to film wolves on Deadly before,
0:07:47 > 0:07:49and it's always one of our toughest challenges.
0:07:51 > 0:07:54But after a day and a half of endless driving,
0:07:54 > 0:07:56staring desperately off into the snow,
0:07:56 > 0:07:58finally a sighting.
0:07:59 > 0:08:01Go, go, go!
0:08:01 > 0:08:05Don't worry, just bring it round to the front with you, Stevo.
0:08:07 > 0:08:08There's two wolves!
0:08:16 > 0:08:22We've just seen a couple of wolves walking towards the road.
0:08:22 > 0:08:25At the moment they're about a mile away,
0:08:25 > 0:08:28but it's possible they could come close enough that we can get
0:08:28 > 0:08:31a shot of them on the camera.
0:08:31 > 0:08:35The wolf's been my favourite animal for many years,
0:08:35 > 0:08:38but in the wild I've only caught fleeting glimpses of them.
0:08:38 > 0:08:40They're so, so hard to film.
0:08:40 > 0:08:46I mean, it's not an endangered animal, there are still thousands
0:08:46 > 0:08:50of them here in North America, but no-one ever sees them.
0:08:50 > 0:08:53They are very, very shy, very elusive animals,
0:08:53 > 0:08:57and the chance of seeing one relatively close
0:08:57 > 0:09:00in the middle of the day is incredibly exciting.
0:09:00 > 0:09:02Let's just get off the road.
0:09:04 > 0:09:07This is great, yeah, this is great.
0:09:09 > 0:09:12Oh, wow!
0:09:12 > 0:09:13They're trotting on so quick cos...
0:09:16 > 0:09:22- BREATHLESS:- Yeah, that's fantastic, two wolves out in the open.
0:09:24 > 0:09:27And really closer than I expected to get.
0:09:31 > 0:09:35So what we've got is a male and a female wolf,
0:09:35 > 0:09:38at least one of them is wearing a radio collar,
0:09:38 > 0:09:40that's put on by biologists so that they can track
0:09:40 > 0:09:43the movements of these animals and make sure they keep them safe.
0:09:43 > 0:09:46Phew. Oh, they're so beautiful.
0:09:50 > 0:09:52'I can't tell you how rare this is.
0:09:52 > 0:09:55'Some people live their whole lives in this region
0:09:55 > 0:09:56'without seeing a wolf.
0:09:56 > 0:10:00'Seeing them run free here in broad daylight is even more special,
0:10:00 > 0:10:02'because 30 years ago they'd been wiped out
0:10:02 > 0:10:05'from most of the United States.
0:10:05 > 0:10:07'Now, this top predator is making a comeback.'
0:10:09 > 0:10:13This is really, really exciting. My heart's going crazy.
0:10:13 > 0:10:17Here he comes, coming almost at a trot,
0:10:17 > 0:10:19that loping gait, wolves can keep that up
0:10:19 > 0:10:21for a great deal of time if they have to.
0:10:21 > 0:10:24That's one of their big advantages when they're hunting,
0:10:24 > 0:10:26is their endurance. Heading towards the road,
0:10:26 > 0:10:29it looks like it might cross right in front of that car up there.
0:10:30 > 0:10:31Oh, look at that!
0:10:39 > 0:10:42The most incredible view of a wild wolf ever.
0:10:47 > 0:10:50Well, it was chaotic, but it was very, very exciting
0:10:50 > 0:10:52and a sight that most wildlife watchers
0:10:52 > 0:10:54would give their right arm for.
0:10:54 > 0:10:57You have to say, wolves in the winter wonderland
0:10:57 > 0:11:00- massive success and definitely Deadly.
0:11:05 > 0:11:07Phenomenal endurance hunters.
0:11:09 > 0:11:11With jaws that can crush bone.
0:11:13 > 0:11:16An unparalleled intelligent pack predator.
0:11:18 > 0:11:19There's no doubt that
0:11:19 > 0:11:20wolves are Deadly.
0:11:20 > 0:11:23VOICE WHISPERS: Deadly!
0:11:24 > 0:11:26So the wolf may be the top of the line predator
0:11:26 > 0:11:28here in the Yellowstone snow,
0:11:28 > 0:11:32but it is nothing like the biggest or most powerful animal here.
0:11:32 > 0:11:35That creature...has a skull...
0:11:38 > 0:11:39..that looks like this.
0:11:41 > 0:11:48This belongs to the largest land mammal found on the whole continent
0:11:48 > 0:11:50- the bison.
0:11:51 > 0:11:54Weighing as much as a tonne, these raging bulls
0:11:54 > 0:11:57are a formidable force to be reckoned with.
0:11:57 > 0:11:59Bison injure more people in Yellowstone
0:11:59 > 0:12:01than wolves and grizzly bears put together.
0:12:03 > 0:12:04And as we're tracking them on foot,
0:12:04 > 0:12:06we need to keep sharp.
0:12:10 > 0:12:11They're through the trees here,
0:12:11 > 0:12:14the snow's going to be very, very deep,
0:12:14 > 0:12:17possibly waist, even chest-deep, so we've got snowshoes on
0:12:17 > 0:12:20to try and keep us up above it as much as possible.
0:12:20 > 0:12:23'But even with snow shoes, we're struggling.'
0:12:24 > 0:12:25HE LAUGHS
0:12:25 > 0:12:27- Having trouble there, Aaron? - Uh?
0:12:27 > 0:12:29- Are you having trouble there? - No, it's fine.
0:12:31 > 0:12:35We're heading for a meadow where we hope the bison will be feeding,
0:12:35 > 0:12:38and all the kit needs to be dragged in my sled.
0:12:38 > 0:12:41It feels like I'm towing a truck behind me.
0:12:43 > 0:12:46Now this is what I've been really hoping to find.
0:12:48 > 0:12:52It's a bison track, AND...look at that!
0:12:58 > 0:13:02It's... Oh, it's very fresh, it's fresher than I expected!
0:13:02 > 0:13:04That is bison poo!
0:13:05 > 0:13:07- Oh. - HE SNIFFS
0:13:07 > 0:13:10Really, really fresh, laid within the last hour or so,
0:13:10 > 0:13:12in fact, it's still warm inside,
0:13:12 > 0:13:15you could put your hands into it and use it as a glove.
0:13:17 > 0:13:19'Yeah, I don't think that'll catch on.
0:13:19 > 0:13:21'Still, it means we're close.
0:13:21 > 0:13:24'And then, through the trees, we get our first glimpse.'
0:13:31 > 0:13:34So, ahead of us is exactly what we'd hoped for.
0:13:36 > 0:13:39The bison are still a decent distance away,
0:13:39 > 0:13:40but once we start getting closer
0:13:40 > 0:13:43we're going to have to be really quite careful.
0:13:53 > 0:13:55BISON GROWL AND SNORT
0:13:58 > 0:14:00Bison are bovids,
0:14:00 > 0:14:03or bovine animals, which means they're in the cow family.
0:14:03 > 0:14:07If your idea of a cow is a big friendly Friesian
0:14:07 > 0:14:10chewing the cud, then you couldn't be more wrong.
0:14:10 > 0:14:13I mean, this is a group of animals that contains things
0:14:13 > 0:14:16like the water buffalo, the Cape buffalo and the bison themselves.
0:14:16 > 0:14:19These are creatures that are deceptively fast,
0:14:19 > 0:14:20very strong and powerful,
0:14:20 > 0:14:23and can be very grumpy and unpredictable.
0:14:27 > 0:14:30During their summertime rut, male bison show off
0:14:30 > 0:14:33their full lethal potential when they joust for females.
0:14:37 > 0:14:40These beefy battering rams slam into each other
0:14:40 > 0:14:43with enough force to crumple steel.
0:14:43 > 0:14:47The strongest male with the thickest skull gets the girl,
0:14:47 > 0:14:49and all these brutal, bulky battles
0:14:49 > 0:14:52produce bulls that can really take care of themselves.
0:15:02 > 0:15:06They are incredibly powerful animals, and a lot of that
0:15:06 > 0:15:08you can see in the muscularity behind the head.
0:15:08 > 0:15:12There's a huge hump which is just muscle, used to hold up that
0:15:12 > 0:15:17huge bony skull. These animals will use those in battles
0:15:17 > 0:15:20with each other, but also in fighting off their mortal enemy
0:15:20 > 0:15:21- the wolf.
0:15:25 > 0:15:27The battles between bison and wolves
0:15:27 > 0:15:29are a showdown of brains versus brawn.
0:15:34 > 0:15:37Like a wolf pack, bison have strength in numbers.
0:15:40 > 0:15:43And their most effective defence is stampeding.
0:15:47 > 0:15:49Bulldozing through deep snow,
0:15:49 > 0:15:51the herd is like an unstoppable freight train.
0:15:54 > 0:15:57The largest animals form an outer wall of muscle,
0:15:57 > 0:16:00hooves and horns - protecting the smaller, weaker ones.
0:16:01 > 0:16:04Often the wolves will realise they're outnumbered and outgunned,
0:16:04 > 0:16:05and will just leave hungry.
0:16:07 > 0:16:08But when they do go into combat,
0:16:08 > 0:16:11it's a brutal spectacle.
0:16:11 > 0:16:14The wolves have bite, guile, grit and determination.
0:16:14 > 0:16:18The bison have horns that could pierce through a car door,
0:16:18 > 0:16:20and kicks that can shatter bone.
0:16:21 > 0:16:25WOLF WHINES AND BISON GRUNTS
0:16:25 > 0:16:28As a deadly defender, they demand respect,
0:16:28 > 0:16:30even from the fiercest of predators.
0:16:33 > 0:16:34Oh, he's coming.
0:16:34 > 0:16:38'And back at the car, we got a first-hand reminder
0:16:38 > 0:16:41'when a large male caught us by surprise.'
0:16:41 > 0:16:44- Everyone, come, come this way. - Be careful, Steve.
0:16:45 > 0:16:47We need to get right back to the car, guys.
0:16:52 > 0:16:54You need to back up a bit. Guys, back,
0:16:54 > 0:16:59Johnny, back. Maybe behind the car. Johnny.
0:17:05 > 0:17:08Nothing is going to get in the way of this bison juggernaut.
0:17:12 > 0:17:13Fantastic.
0:17:19 > 0:17:21Weighing a tonne.
0:17:23 > 0:17:26With lethal dagger like-horns.
0:17:28 > 0:17:30Capable of stampeding at 30mph.
0:17:31 > 0:17:35Bison are bovine bad boys, and decidedly...
0:17:35 > 0:17:36VOICE WHISPERS: Deadly!
0:17:40 > 0:17:43We're now travelling deep into the remotest part of Yellowstone.
0:17:46 > 0:17:49Here I'm hoping to find some very specialist predators
0:17:49 > 0:17:52that have learned how to survive this frozen heartland.
0:17:55 > 0:17:57There's a bald eagle sat on a tree.
0:17:59 > 0:18:00(Wow!)
0:18:02 > 0:18:03What a sight!
0:18:06 > 0:18:09Our base camp is right in the middle of Yellowstone,
0:18:09 > 0:18:13surrounded by endless wilderness.
0:18:13 > 0:18:17We're going to be staying in these kind of garden shed things,
0:18:17 > 0:18:20they're called lavvu, this one's mine right here.
0:18:20 > 0:18:23It looks kind of cosy. All right, what else have we got?
0:18:23 > 0:18:26We've got stacks of skis for getting around,
0:18:26 > 0:18:28really important in the snow,
0:18:28 > 0:18:30but out there is the snowy wilderness
0:18:30 > 0:18:32that we've come here to explore.
0:18:34 > 0:18:38'And the nearby frozen river offers up our first surprise specialist.'
0:18:43 > 0:18:45Ah, yes, well spotted.
0:18:45 > 0:18:47'If only this water weasel would stay still long enough
0:18:47 > 0:18:49'for us to get a shot.'
0:18:50 > 0:18:52Yes, otter! Got it.
0:18:54 > 0:18:55He's just dived into the ice.
0:18:57 > 0:18:59Really quick, isn't he?
0:19:00 > 0:19:03'Otters can travel a quarter of a mile underwater on a
0:19:03 > 0:19:07'single breath, there's no way of guessing where he'll pop up next.'
0:19:10 > 0:19:12He is leading us a merry dance!
0:19:13 > 0:19:16I've totally lost him, I've got no idea where he is.
0:19:16 > 0:19:17HE LAUGHS
0:19:19 > 0:19:23This otter is definitely foraging or looking for food,
0:19:23 > 0:19:26so as he's moving up the river he's doing repeated dives,
0:19:26 > 0:19:29heading down probably towards the bed.
0:19:31 > 0:19:33There he is, Johnny, Johnny! Really clear.
0:19:37 > 0:19:38Oh, wow!
0:19:40 > 0:19:44'Out of the water we get a glimpse of the streamlined body and
0:19:44 > 0:19:48'long muscular tail that make otters such agile underwater hunters.'
0:19:50 > 0:19:54They are constantly in and out of the water searching for food,
0:19:54 > 0:19:56and that could be a decent-sized fish,
0:19:56 > 0:20:02it could be things like crayfish, or it could be water birds, frogs.
0:20:02 > 0:20:04They are extraordinary predators.
0:20:07 > 0:20:10Underwater, otters come into their own. They're superbly agile,
0:20:10 > 0:20:13with a bendy spine and short limbs they can twist
0:20:13 > 0:20:16and turn towards prey, which they target with
0:20:16 > 0:20:18long tactile whiskers.
0:20:18 > 0:20:21The whiskers are so sensitive that the otter can
0:20:21 > 0:20:25perceive prey in murky or pitch-black night-time waters.
0:20:25 > 0:20:28They can even track a fish's movements by
0:20:28 > 0:20:29the invisible wake it leaves behind.
0:20:32 > 0:20:34They can hunt as family groups
0:20:34 > 0:20:36and take fish almost as big as themselves.
0:20:42 > 0:20:46Needle-sharp teeth and claws hold on to their slippery suppers.
0:20:51 > 0:20:53They have the ability to gorge themselves,
0:20:53 > 0:20:55eating 20% of their body weight a day,
0:20:55 > 0:20:58even here in Yellowstone's icy rivers.
0:20:58 > 0:21:03These ultra tough, aquatic acrobats are a real find.
0:21:03 > 0:21:05(Oh, Johnny, Johnny, Johnny!)
0:21:10 > 0:21:11(It's just down below us.)
0:21:12 > 0:21:13(Looking straight at us.)
0:21:15 > 0:21:16(Beautiful.)
0:21:20 > 0:21:25Ah, this is brilliant. He's just rolling on his back
0:21:25 > 0:21:29on the ice, like he's having a really good scratch.
0:21:31 > 0:21:32That is brilliant.
0:21:34 > 0:21:36It's hard to believe when you see them
0:21:36 > 0:21:40like this, just looking like a big teddy bear,
0:21:40 > 0:21:42that this animal could be one of the
0:21:42 > 0:21:44most voracious predators you will ever see.
0:21:46 > 0:21:49'So, the otter's a genuine contender.'
0:21:51 > 0:21:54But there are plenty more snow-time specialists here.
0:21:54 > 0:21:56And they've left a story behind in the snow.
0:22:00 > 0:22:02There's a really interesting trail of tracks
0:22:02 > 0:22:04running over this flat slope in front of us,
0:22:04 > 0:22:07and you can see where a fox has come along.
0:22:07 > 0:22:10And it's been walking in a track and it's,
0:22:10 > 0:22:12it's going round in big circles.
0:22:12 > 0:22:15Oh, very, very fresh, he's certainly still in the area.
0:22:17 > 0:22:19Could well be watching us right now.
0:22:21 > 0:22:22'And sure enough...'
0:22:24 > 0:22:26Wow!
0:22:29 > 0:22:31'..the fox is just 50 metres away.'
0:22:33 > 0:22:35(Look at that, isn't he pretty?)
0:22:36 > 0:22:40He is definitely on the hunt, nose down
0:22:40 > 0:22:43close to the snow, listening, smelling,
0:22:43 > 0:22:45all his senses on high alert.
0:22:47 > 0:22:49'Red foxes are in the dog family like wolves,
0:22:49 > 0:22:52'but have very different lives.
0:22:52 > 0:22:55'They're a great opportunist and can find a meal almost anywhere.
0:22:56 > 0:22:58'They have adapted to live in forests,
0:22:58 > 0:23:01'deserts and even cities, but I've never seen them looking
0:23:01 > 0:23:02'more majestic than here.'
0:23:05 > 0:23:10That's so beautiful. Wow.
0:23:14 > 0:23:18The small rodents the red foxes like to snack on
0:23:18 > 0:23:21very, very rarely come out into the open, even at night
0:23:21 > 0:23:24at this time of year. Instead they're scuttling around in tunnels
0:23:24 > 0:23:27underneath the snow, and the red fox can hear them moving,
0:23:27 > 0:23:31even as much as my height in depth beneath the snow,
0:23:31 > 0:23:34it'll still hear their movements, the ears are that sensitive.
0:23:37 > 0:23:40Pinpointing their prey is just the start.
0:23:40 > 0:23:42Next, they have to catch it.
0:23:43 > 0:23:48Its hunting strategy is, well, as cunning as a fox!
0:24:00 > 0:24:05Punching down into the snow, it's hit the jackpot.
0:24:07 > 0:24:10An unsuspecting vole becomes lunch.
0:24:11 > 0:24:14This is truly one of the ultimate ambush specialists.
0:24:16 > 0:24:19Well, they might be the smallest member of the dog family here,
0:24:19 > 0:24:22but they're still undeniably lethal.
0:24:27 > 0:24:30They can track prey under two metres of snow.
0:24:31 > 0:24:34Adaptable enough to survive almost anywhere.
0:24:36 > 0:24:37A silent assassin.
0:24:39 > 0:24:41The red fox wins my award for
0:24:41 > 0:24:43best specialist hunter.
0:24:43 > 0:24:45VOICE WHISPERS: Deadly!
0:24:47 > 0:24:50This leg of my Pole to Pole journey has provided
0:24:50 > 0:24:53some spectacular lethal encounters.
0:24:53 > 0:24:55Everyone, come this way.
0:24:56 > 0:24:58But we're not leaving just yet.
0:25:02 > 0:25:04Because Yellowstone has a secret
0:25:04 > 0:25:06more deadly than anything we've seen.
0:25:09 > 0:25:14On the surface this may look like a magical frozen wonderland,
0:25:14 > 0:25:16but something sinister is stirring beneath.
0:25:24 > 0:25:26At various places in Yellowstone you find features
0:25:26 > 0:25:28like these, they're called geysers.
0:25:28 > 0:25:31It's where superheated steam and water rushes to the surface
0:25:31 > 0:25:34and squirts up, it could be as tall as an office block,
0:25:34 > 0:25:36and these are all a clue that there's something
0:25:36 > 0:25:41pretty special and very, very dangerous happening beneath my feet.
0:25:41 > 0:25:44The geysers are being heated by a force of nature
0:25:44 > 0:25:47so earth-shatteringly massive it's hard to get your head around.
0:25:50 > 0:25:55Yellowstone sits in the 50 mile-wide crater of a super volcano.
0:25:57 > 0:26:00If it erupts, it could be the largest natural disaster
0:26:00 > 0:26:02in the history of humankind.
0:26:09 > 0:26:11It will have a force thousands of times
0:26:11 > 0:26:13greater than a normal volcano.
0:26:17 > 0:26:22MUSIC: "Earthquake" by Labrinth
0:26:22 > 0:26:25Enough power to blast away entire mountains,
0:26:25 > 0:26:29throwing hundreds of miles of rock and debris into the atmosphere.
0:26:37 > 0:26:39Most of the United States could be covered
0:26:39 > 0:26:41in a blanket of ash and rock.
0:26:42 > 0:26:46Dust clouds would obscure the sun for months all over the world,
0:26:46 > 0:26:48causing global temperature to plummet.
0:26:48 > 0:26:51It could trigger a new ice age.
0:26:51 > 0:26:53Even the tropics could end up looking like
0:26:53 > 0:26:55Yellowstone does right now.
0:26:56 > 0:27:00It tends to erupt about every 600,000 years.
0:27:00 > 0:27:03The last time it erupted was about 640,000 years ago,
0:27:03 > 0:27:04so we're well overdue.
0:27:04 > 0:27:07A super volcano that could completely change
0:27:07 > 0:27:09the course of life as we know it.
0:27:09 > 0:27:11That is definitely Deadly!
0:27:14 > 0:27:15A slumbering giant.
0:27:18 > 0:27:21And possibly the most powerful force of nature on the planet.
0:27:25 > 0:27:27Yellowstone's super volcano
0:27:27 > 0:27:29is as deadly as it gets.
0:27:29 > 0:27:30VOICE WHISPERS: Deadly!
0:27:33 > 0:27:36Join me next time as I continue my journey
0:27:36 > 0:27:38on Deadly Pole To Pole.
0:27:38 > 0:27:39HE HOWLS
0:27:39 > 0:27:40WOLF HOWLS
0:27:42 > 0:27:45Subtitles by Red Bee Media Ltd